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| Torque increase on a 7x? |
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| SKIPRAT:
Hi There I have found an article on the UK mini lathe site about increasing torque on the mini lathe it mentions some pulley sizes and gear ratios.there is a lot of other stuff regarding the mini lathe i hope this will be of use to you . Cheers Paul http://www.mini-lathe.org.uk/torque_gear_replace.shtml |
| Sorekiwi:
One of the popular modifications for this on the Yahoo sites is a jackshaft arrangement by Ralph Patterson. There are photographs and drawings here: http://www.toolsandmods.com/library/ralph_patterson_speed_reducer_1.pdf In a nutshell the motor is replaced by a jackshaft and another set of the original pulleys (and belt) are used to do another speed reduction. According to those who have done it, it works well. I bought another belt and pair of pulleys 3 or 4 years ago, but havent got around to building the rest of the bits. I never use the high range on my minilathe, so I think its a viable solution. Another thought is that there have been posts on here about increasing torque on the Sieg mini-mills by substituting a KB motor controller. I assume that that controller would have a similar effect on the lathe as well? :offtopic: but while you are on that website... Another very useful mod that Ralph Patterson has drawn is the "Fine Feed Modification" which is a modification to the leadscrew gear banjo to allow another pair of gears to drive the leadscrew. Using another pair of 20/80 gears in the train will give a leadscrew ratio of 1024:1 as opposed to the standard fine feed of 256:1. With a nice sharp tool and the fine feed engaged I have managed some beautiful finishes with this set-up. |
| picclock:
@ Andyf My lathe is a real Bull, and the speed difference between forward and reverse is minimal. If there had been a large difference it would be caused by the controller, and simply fixed by swapping the motor leads round. These just plug into the speed controller board so its simple to do. The motor is a permanent magnet type with no position adjustment for the brushes. I suspect that these are generic parts sold as bi-directional motors. The motor shaft is extended by about 12mm by an adapter made out of a broken pry bar. It works very well but does tend to be noisy. A quieter solution is to use two belt drives to achieve the desired ratio. @Sorekiwi You can see the banjo mod in the link posted in my earlier post (6 posts prior). It makes life a lot easier with fewer adjustments needed to set a given reduction. I now use a home brewed electronic lead screw controller, which gives feeds down to 30 thou per minute so the only time the gears are used is for thread cutting. Because its combined with a cheapo caliper the lathe can be set to do repeated passes with just one touch of the button, and it will turn the required length and then rewind the carriage back to the start ready for the next pass. If I had thought to make the cross slide motorised it would just be a case of setting the length and depth and hitting the button. I made it because turning stuff on large diameter metal is about as interesting as watching grass grow - this way I just set the cross slide depth, touch the button and :coffee: - I should have called it the sanity saver :thumbup: piccy on :- http://i917.photobucket.com/albums/ad19/picclock/Cheapo%20Electronic%20Leadscrew/Leadscrewdriver.jpg Best Regards picclock |
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